A series of dinuclear Pt(II) complexes of the type [Pt2(N,N,N',N'-tetrakis(2-pyridylmethyl)diamine(H2O)2]4+ were synthesized. Acid-base titrations, and concentration and temperature dependent stopped-flow measurements of the reaction with chloride were performed to study the thermodynamic and kinetic behaviour of the dinuclear bridged complexes. The results indicate that there is a clear interaction between the two Pt(II) centres, which becomes weaker as the aliphatic chain increases in length. From a certain chain length onwards, the Pt(II) centres become independent of each other and exhibit identical thermodynamic and kinetic properties. The experimental results are discussed in reference to structures obtained by DFT (BP86/LACVP*) calculations.

Complexes of the type [Pt2(N,N,N',N'-tetrakis(2-pyridylmethyl)diamine(HO)2]4+ and [Pt2(N,N,N',N'-tetrakis(2-pyridylmethyl)diamine(Cl)2]2+ were used to study their reactions with a series of bio-relevant nucleophiles, viz. thiourea, L-methionine and guanosine-5'-monophosphate (5'-GMP2-) as a function of nucleophile concentration and temperature. The reactions with the sulfur containing nucleophiles (thiourea and L-methionine) were followed under pseudo-first-order conditions by stopped-flow and UV-Vis spectrophotometry. The reaction with 5'-GMP2- was carried out under second order conditions and studied by NMR spectroscopy. The results indicate that the bridged dinuclear complexes remain intact after coordination of the studied nucleophiles for an extended period of time, which differs significantly from that reported for other multinuclear platinum complexes in the literature.

The dinuclear PtII complexes bis{[(1R,2R)‐(–)‐1,2‐diaminocyclohexane]chloroplatinum(II)}(μ‐1,8‐octanediamine), bis{[(1R,2R)‐(–)‐1,2‐diaminocyclohexane]chloroplatinum(II)}(μ‐1,10‐decanediamine) and bis{[(1R,2R)‐(–)‐1,2‐diaminocyclohexane]chloroplatin(II)}[μ‐1,4‐bis(3‐pyridyl)buta‐1,3‐diyne] were synthesized. Acid‐base titrations and concentration and temperature dependent measurements of the reactions with chloride and thiourea were performed to study the influence of the nature of the bridging ligand on the thermodynamic and kinetic properties of the complexes. The reactions with chloride and thiourea were followed under pseudo‐first‐order conditions by stopped‐flow and UV/Vis spectrophotometry. The results indicate that the bridging ligand has an influence on the reactivity and stability of the complexes towards nucleophiles as well as on possible electronic interactions between the two PtII centres. The experimental results are discussed in reference to structures obtained by DFT (BP86/LACVP*) calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)